NASA Reignites Program for Nuclear Thermal Rockets

In its pursuit of missions that will take us back to the Moon, to Mars, and beyond, NASA has been exploring a number of next-generation propulsion concepts. Whereas existing concepts have their advantages – chemical rockets have high energy density and ion engines are very fuel-efficient – our hopes for the future hinge on us finding alternatives that combine efficiency and power.

To this end, researchers at NASA’s Marshall Space Flight Center are once again looking to develop nuclear rockets. As part of NASA’s Game Changing Development Program, the Nuclear Thermal Propulsion (NTP) project would see the creation of high-efficiency spacecraft that would be capable of using less fuel to deliver heavy payloads to distant planets, and in a relatively short amount of time.

As Sonny Mitchell, the project of the NTP project at NASA’s Marshall Space Flight Center, said in a recent NASA press statement:

“As we push out into the solar system, nuclear propulsion may offer the only truly viable technology option to extend human reach to the surface of Mars and to worlds beyond. We’re excited to be working on technologies that could open up deep space for human exploration.”

Nuclear reactors (like the one pictured here) are being considered by NASA’s Marshall Space Flight Center for possible future missions. Credit: NASA

To see this through, NASA has entered into a partnership with BWX Technologies (BWXT), a Virginia-based energy and technology company that is a leading supplier of nuclear components and fuel to the U.S. government. To assist NASA in developing the necessary reactors that would support possible future crewed missions to Mars, the company’s subsidiary (BWXT Nuclear Energy, Inc.) was awarded a three-year contract worth $18.8 million.

During this three years in which they will be working with NASA, BWXT will provide the technical and programmatic data needed to implement NTP technology. This will consist of them manufacturing and testing prototype fuel elements and helping NASA to resolve any nuclear licensing and regulatory requirements. BWXT will also aid NASA planners in addressing the issues of feasibility and affordably with their NTP program.

As Rex D. Geveden, BWXT’s President and Chief Executive Officer, said of the agreement:

“BWXT is extremely pleased to be working with NASA on this exciting nuclear space program in support of the Mars mission. We are uniquely qualified to design, develop and manufacture the reactor and fuel for a nuclear-powered spacecraft. This is an opportune time to pivot our capabilities into the space market where we see long-term growth opportunities in nuclear propulsion and nuclear surface power.”

In an NTP rocket, uranium or deuterium reactions are used to heat liquid hydrogen inside a reactor, turning it into ionized hydrogen gas (plasma), which is then channeled through a rocket nozzle to generate thrust. A second possible method, known as Nuclear Electric Propulsion (NEC), involves the same basic reactor converted its heat and energy into electrical energy which then powers an electrical engine.

Artist’s concept of a Bimodal Nuclear Thermal Rocket in Low Earth Orbit. Credit: NASA

In both cases, the rocket relies on nuclear fission to generates propulsion rather than chemical propellants, which has been the mainstay of NASA and all other space agencies to date. Compared to this traditional form of propulsion, both types of nuclear engines offers a number of advantages. The first and most obvious is the virtually unlimited energy density it offers compared to rocket fuel.

This would cut the total amount of propellant needed, thus cutting launch weight and the cost of individual missions. A more powerful nuclear engine would mean reduced trip times. Already, NASA has estimated that an NTP system could make the voyage to Mars to four months instead of six, which would reduce the amount of radiation the astronauts would be exposed to in the course of their journey.

To be fair, the concept of using nuclear rockets to explore the Universe is not new. In fact, NASA has explored the possibility of nuclear propulsion extensively under the Space Nuclear Propulsion Office. In fact, between 1959 and 1972, the SNPO conducted 23 reactor tests at the Nuclear Rocket Development Station at AEC’s Nevada Test Site, in Jackass Flats, Nevada.

In 1963, the SNPO also created the Nuclear Engine for Rocket Vehicle Applications (NERVA) program to develop nuclear-thermal propulsion for long-range crewed mission to the Moon and interplanetary space. This led to the creation of the NRX/XE, a nuclear-thermal engine which the SNPO certified as having met the requirements for a crewed mission to Mars.

Artist’s concept of a bimodal nuclear rocket slowing down to establish orbit around Mars. Credit: NASA

The Soviet Union conducted similar studies during the 1960s, hoping to use them on the upper stages of  of their N-1 rocket. Despite these efforts, no nuclear rockets ever entered service, owing to a combination of budget cuts, loss of public interest, and a general winding down of the Space Race after the Apollo program was complete.

But given the current interest in space exploration, and ambitious mission proposed to Mars and beyond, it seems that nuclear rockets may finally see service. One popular idea that is being considered is a multistage rocket that would rely on both a nuclear engine and conventional thrusters – a concept known as a “bimodal spacecraft”. A major proponent of this idea is Dr. Michael G. Houts of the NASA Marshall Space Flight Center.

In 2014, Dr. Houts  conducted a presentation outlining how bimodal rockets (and other nuclear concepts) represented “game-changing technologies for space exploration”. As an example, he explained how the Space Launch System (SLS) – a key technology in NASA’s proposed crewed mission to Mars – could be equipped with chemical rocket in the lower stage and a nuclear-thermal engine on the upper stage.

In this setup, the nuclear engine would remain “cold” until the rocket had achieved orbit, at which point the upper stage would be deployed and the reactor would be activated to generate thrust. Other examples cited in the report include long-range satellites that could explore the Outer Solar System and Kuiper Belt and fast, efficient transportation for manned missions throughout the Solar System.

The company’s new contract is expected to run through Sept. 30th, 2019. At that time, the Nuclear Thermal Propulsion project will determine the feasibility of using low-enriched uranium fuel. After that, the project then will spend a year testing and refining its ability to manufacture the necessary fuel elements. If all goes well, we can expect that NASA’s “Journey to Mars” might just incorporate some nuclear engines!

Further Reading: NASA, BWXT News

The Orion’s Heat Shield Gets a Scorching on Re-entry

Yes, she’s a little worse for wear, isn’t she? But then again, that’s what atmospheric re-entry and 2200 °Celsius (4000 °Fahrenheit) worth of heat will do to you! Such was the state of the heat shield that protected NASA’s Orion Spaceship after it re-entered the atmosphere on Dec. 5th, 2014. Having successfully protected the craft during it’s test flight, the shield was removed and transported to the Marshall Space Flight Center in Huntsville, Alabama, where it arrived on March. 9th.

Since that time, a steady stream of NASA employees have been coming by the facility to get a look at it while engineers collect data and work to repair it. In addition to being part of a mission that took human-rated equipment farther out into space than anything since the Apollo missions, the heat shield is also living proof that NASA is restoring indigenous space capability to the US.

First unveiled by NASA in May of 2011, the Orion Multi-Purpose Crew Vehicle (MPCV) was intrinsic to the Obama administration’s plan to send astronauts to a nearby asteroid by 2025 and going to Mars by the mid-2030’s. In addition to facilitating these long-range missions, the Orion spacecraft would also handle some of the routine tasks of spaceflight, such as providing a means of delivering and retrieving crew and supplies from the ISS.

NASA Orion spacecraft blasts off atop 1st  Space Launch System rocket in 2017 - attached to European provided service module – on an enhanced m mission to Deep Space where an asteroid could be relocated as early as 2021.   Credit: NASA
Artist’s concept of the Orion spacecraft being sent into orbit atop the first Space Launch System (SLS) rocket in 2017. Credit: NASA

The uncrewed test flight that took place on December 5, 2014, known as Exploration Flight Test 1 (EFT-1), was intended to test various Orion systems, including separation events, avionics, heat shielding, parachutes, and recovery operations prior to its debut launch aboard the Space Launch System,

This design of this mission corresponded to the Apollo 4 mission of 1967, which demonstrated the effectiveness of the Apollo flight control systems and the heat shields ability to withstand re-entry conditions, as part of the spacecraft’s return from lunar missions.

After being retrieved, the heat shield was transported by land to the Marshall Space Flight Center, where it was offloaded and transferred to a large support structure so engineers could perform studies on it for the next three months.

This will consist of collecting samples from the shield to measure their char layers and degree of erosion and ablation, as well as extracting the various instruments embedded in the heat shield to assess their performance during re-entry.

The heat shield arrived March 9 at Marshall, where experts from the Center and NASA’s Ames Research Center will extract samples of the ablative material, or Avcoat. Image Credit:  NASA/MSFC/Emmett Given
The heat shield arriving at Marshall on March 9th, where experts from the Center and NASA’s Ames Research Center. Credit: NASA/MSFC/Emmett Given

After the analysis is complete, technicians will load the shield into the 7-axis milling machine and machining center, where it will be grind down to remove the remaining material covering. Known as Avcoat, this heat-retardant substance is similar to what the Apollo missions used, with the exception of toxic materials like asbestos.

This material is used to fill the 320,000 honeycomb-like cells that make up the outer layer of the shield. When heated, the material burns away (aka. ablates) in order to prevent heat being transferred into the crew module. This shield is placed over the craft’s titanium skeleton and carbon-fiber skin, providing both protection and insulation for the interior.

Once all the Avcoat is removed and only the skeletal frame remains, it will be shipped to the Langley Research Center in Hampton, Virginia, for more tests. Since the Orion was returning from a greater distance in space than anything since Apollo, it experienced far greater heat levels than anything in recent decades, reaching as high as 2200 °C (4000 °F).

During Orion's test flight the heat shield reached temperatures of about 4,000 degrees Fahrenheit. Instrumentation in the heat shield measured the rise of the surface and internal temperatures during re-entry as well as heating levels and pressures. Image Credit:  NASA/MSFC/Emmett Given
Instrumentation in the Orion heat shield (visible here) measured the rise of the surface and internal temperatures during re-entry. Credit: NASA/MSFC/Emmett Given

Instrumentation in the shield measured the rise of the surface and internal temperatures during re-entry as well as the ablation rate of the shield’s coating. Over the next few months, NASA experts will be pouring over this data to see just how well the Orion shield held up under extreme heat. But so far, the results look positive – with only 20% of the Avcoat burning away on the test-flight re-entry.

In the future, the Orion spacecraft will be launched on Space Launch System on missions that will take it to nearby asteroids and eventually Mars. The first mission to carry astronauts is not expected to take place until 2021 at the earliest.

Further Reading: NASA

NASA Celebrates Return To Work, But Shutdown’s Shadow Could Linger

After 16 days off the job, most employees at NASA returned to work today (Oct. 17). The good news came after a late-night deal by U.S. politicians to reopen government activities until Jan. 15 and raise the debt limit — originally expected to expire today — until Feb. 7. Democrats and Republicans were battling over the implementation of a new health care law; more details on how the deal was reached are available in this New York Times article.

During the shutdown, only mission-essential functions at NASA were completed except at areas such as the Jet Propulsion Laboratory, which are run by contractors. Twitter, Facebook and social media updates went silent. Missions were run on a needs-only basis, and for a while it looked as though the upcoming MAVEN mission to Mars might be delayed (although it got an exception due to its role as a communications relay for NASA’s rovers.)

So you can imagine the happiness on social media when NASA employees returned to work.

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Given the length of the shutdown,  not all work can just start immediately. Experiments have been left unattended for more than two weeks. Equipment needs to be powered back on. Cancelled meetings and travel arrangements need to, as it is possible, be rebooked.

At NASA’s Marshall Space Flight Center, spokesperson Don Amatore asked employees to be mindful of safety precautions, according to All Alabama. He also stated that “liberal leave” is in effect for employees today and on Friday, meaning that employees are able to take time off without requesting it beforehand — as long as their supervisors know.

Several Twitter reports from NASA contractors on Thursday also indicated that they were unsure if they would be coming back to work on that day, or at some point in the near future. The agency, however, was reportedly sending automated telephone updates to employees and contractors advising them to check with their supervisors for information.

The Stratospheric Observatory for Infrared Astronomy, or SOFIA, 747SP basks in the light of a full moon shining over California’s Mojave Desert. NASA photographer Tom Tschida shot this telephoto image on October 22, 2010 NASA Photo / Tom Tschida
The Stratospheric Observatory for Infrared Astronomy, or SOFIA, 747SP basks in the light of a full moon shining over California’s Mojave Desert. Photo / Tom Tschida

The long-term effects of the shutdown are still coming to light. Certain NASA researchers who planned Antarctic work this year may lose their entire field season. Also, some researchers using NASA or government telescopes missed their “window” of telescope time. “SOFIA remains grounded as a testament to stupidity. Europa keeps her secrets,” wrote Mike Brown,  a professor of planetary astronomy at the California Institute of Technology, on Twitter Oct. 13 about NASA’s Stratospheric Observatory for Infrared Astronomy.

Additionally, the S&P ratings agency noted that the U.S. economy lost $24 billion due to the shutdown, which is more than the initial $17.7 billion request for NASA’s budget in fiscal 2014. Given the agency is in the midst of budget negotiations and is worried about the viability of the commercial crew program, among other items, any long-term economic damage could hurt NASA for a while.

NASA and other government agencies also have only three months of relative stability until the government reaches another funding deadline. What do you think will happen next? Let us know in the comments.

NASA’s Mighty Eagle Takes Flight; Finds Its Target

No, it’s not a UFO — it’s NASA’s “Mighty Eagle”, a robotic prototype lander that successfully and autonomously found its target during a 32-second free flight test at Marshall Space Flight Center yesterday, August 16.

You have to admit though, Mighty Eagle does bear a resemblance to classic B-movie sci-fi spacecraft (if, at only 4 feet tall, markedly less threatening to the general populace.)

Fueled by 90% pure hydrogen peroxide, Mighty Eagle is a low-cost “green” spacecraft designed to operate autonomously during future space exploration missions. It uses its onboard camera and computer to determine the safest route to a pre-determined landing spot.

During the August 16 test flight, Mighty Eagle ascended to 30 feet, identified a target painted on the ground 21 feet away, flew to that position and landed safely — all without being controlled directly.

“This is huge. We met our primary objective of this test series — getting the vehicle to seek and find its target autonomously with high precision,” said Mike Hannan, controls engineer at Marshall Space Flight Center. “We’re not directing the vehicle from the control room. Our software is driving the vehicle to think for itself now. From here, we’ll test the robustness of the software to fly higher and descend faster, expecting the lander to continue to seek and find the target.”

In the wake of a dramatically unsuccessful free flight test of the Morpheus craft on August 9, another green lander designed by Johnson Space Center, the recent achievements by the Mighty Eagle team are encouraging.

Here’s a video from a previous test flight on August 8:

Future tests planned through September will have the lander ascend up to 100 feet before landing. Read more here.

The Mighty Eagle prototype lander was developed by the Marshall Center and Johns Hopkins University Applied Physics Laboratory in Laurel, Md., for NASA’s Planetary Sciences Division, Headquarters Science Mission Directorate Image/video: NASA/Marshall Space Flight Center